1/**
2 * \file random.h
3 *
4 * \brief   This file contains the prototypes of helper functions to generate
5 *          random numbers for the purpose of testing.
6 */
7
8/*
9 *  Copyright The Mbed TLS Contributors
10 *  SPDX-License-Identifier: Apache-2.0
11 *
12 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
13 *  not use this file except in compliance with the License.
14 *  You may obtain a copy of the License at
15 *
16 *  http://www.apache.org/licenses/LICENSE-2.0
17 *
18 *  Unless required by applicable law or agreed to in writing, software
19 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
20 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
21 *  See the License for the specific language governing permissions and
22 *  limitations under the License.
23 */
24
25#ifndef TEST_RANDOM_H
26#define TEST_RANDOM_H
27
28#include "mbedtls/build_info.h"
29
30#include <stddef.h>
31#include <stdint.h>
32
33typedef struct {
34    unsigned char *buf; /* Pointer to a buffer of length bytes. */
35    size_t length;
36    /* If fallback_f_rng is NULL, fail after delivering length bytes. */
37    int (*fallback_f_rng)(void *, unsigned char *, size_t);
38    void *fallback_p_rng;
39} mbedtls_test_rnd_buf_info;
40
41/**
42 * Info structure for the pseudo random function
43 *
44 * Key should be set at the start to a test-unique value.
45 * Do not forget endianness!
46 * State( v0, v1 ) should be set to zero.
47 */
48typedef struct {
49    uint32_t key[16];
50    uint32_t v0, v1;
51} mbedtls_test_rnd_pseudo_info;
52
53/**
54 * This function just returns data from rand().
55 * Although predictable and often similar on multiple
56 * runs, this does not result in identical random on
57 * each run. So do not use this if the results of a
58 * test depend on the random data that is generated.
59 *
60 * rng_state shall be NULL.
61 */
62int mbedtls_test_rnd_std_rand(void *rng_state,
63                              unsigned char *output,
64                              size_t len);
65
66/**
67 * This function only returns zeros.
68 *
69 * \p rng_state shall be \c NULL.
70 */
71int mbedtls_test_rnd_zero_rand(void *rng_state,
72                               unsigned char *output,
73                               size_t len);
74
75/**
76 * This function returns random data based on a buffer it receives.
77 *
78 * \p rng_state shall be a pointer to a #mbedtls_test_rnd_buf_info structure.
79 *
80 * The number of bytes released from the buffer on each call to
81 * the random function is specified by \p len.
82 *
83 * After the buffer is empty, this function will call the fallback RNG in the
84 * #mbedtls_test_rnd_buf_info structure if there is one, and
85 * will return #MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise.
86 */
87int mbedtls_test_rnd_buffer_rand(void *rng_state,
88                                 unsigned char *output,
89                                 size_t len);
90
91/**
92 * This function returns random based on a pseudo random function.
93 * This means the results should be identical on all systems.
94 * Pseudo random is based on the XTEA encryption algorithm to
95 * generate pseudorandom.
96 *
97 * \p rng_state shall be a pointer to a #mbedtls_test_rnd_pseudo_info structure.
98 */
99int mbedtls_test_rnd_pseudo_rand(void *rng_state,
100                                 unsigned char *output,
101                                 size_t len);
102
103#endif /* TEST_RANDOM_H */
104